Method of and apparatus for making white-lead pigment from lead-fumes



(No Model.) E. O. BARTLETT.

METHOD 0E AND APPARATUS FOR MAKING WHITE LEAD PGMENT Ptented Feb. 20, 1894.

PROM LEAD PUMES. No. 515,041

rms@ ses .f

UNITED *rnins EAYRE O. BARTLETT, OF JOPLIN, MISSOURI.

METHOD OF AND APPARATUS FOR MAKING WHITE-LEAD PIGMENT FROM LEAD-FUMEVS.

SPECIFICATION forming part of Letters Patent No. 515,041, dated February 20, 1894.

Application tiled April 12, 1893.

To LZZ zul/1,0m, it may concern.'

Be it known that I, EAYRE O. BARTLETT, of Joplin, county of Jasper, State of Missouri, have invented a certain new and useful Method of and Apparatus for Making Vhite- Lead Pigment from Lead-F u mes, of which the following is an exact and true description, reference being had to the accompanying drawing, forming a part hereof.

My invention relates to the manufacture of a white lead pigment from waste or other lead fumes driven off in Various treatments of lead and lead ores, my object being to obtain an increased yield of the white pigment and to obtain a pigment of a superior quality.

The fumes which form the raw material upon which I operate are what are known as waste lead fumes although such fumes are produced not only as a by-product, but by furnaces and treatments especially adapted to produce them. These fumes as a rule consist of lead sulphide and lead sulphate together with some lead oxide and, as a rule, a varying proportion of oxide of zinc and other zinc compounds. There is also present a considerable amount of unconsumed carbon ina finely divided condition. Owing to the presence of this carbon and of the lead sulphide the fumes are of a dark color and a blue tint and I will hereinafter designate such fumes as blue fumes. Heretofore this blue fume has been subjected to various treatments with a view of converting it -into a white pigment. It has been subjected to the action of high heat in the presence of oxygen as it leaves the furnace in which it is generated with a View of burning out the nnconsnmed carbon and oxidizing the lead sulphide, subsequently being passed through cooling tubes and finally separated from the gases by screens. It has also, after having been separated from the gases in the form of blue fume, been blown or thrown into the upper part of aV furnace and over or on top of a clear re with the same object in view. It has also been subjected in mass to the action of high heat as by passing it through a heated retort. But the most generally used process has been to rst cinder the blue fume by collecting it in mass and igniting it, the combustible matter Serial No. 470039.

(No model.)

in the fume being sufficient to support combustion and the combustionA resulting in a cindering of the fume which is then charged into a low cupola furnace together with carbon and slag-forming material; and generallyT also with additional lead-bearing ores or cinder. The result of this treatment is the reduction of the greater part of the lead present to metallic lead and the sublimation of a portion of the lead, generally about one-third thereof, which is driven off in the form of a white compound of lead sulphate in a mixture with some lead oxide and whatever zinc was present in the blue fume. The fume produced bythis last method is superiorin -quality to that produced by the other treatments but contains approximately three times as much Zinc oxide as the blue fume since substantially all of the zinc present is driven off in this form.

The fume produced by the various processes of whitening the fume by burning out.

carbon without smelting or reducing the lead contains more or less lead compounds which, although white in color, are of a gritty consistency and do not form a desirable element for a pigment.

' I have discovered that to produce a white pigment ofthe best quality from the blue fume it is desirable that the lead compounds therein should be first reduced and then recombined with sulphur and oxygen and driven off as a fume or sublimate of lead-sulphate and lead oxide; the resublimed lead fume being then subjected to any desired purifying process and separated from the gases by screening. This action I have satisfied myself is what accounts for the superior quality of the sublimed lead driven off from the low cupola furnace in the process which I have above described; and the object of my present invention is to subject the blue fume to the same metallurgical actions and at the same time to obtain an increased yield of pigment which shall at the same time be of better quality owing to the presence of a smaller percentage of zinc oxide. These results I secure by providing a low cupola furnace with an additional set of tuyeres placed above the tuyeres used to maintain combustion in the furnace and a short distance below the level of the fuel in the furnace-say from four to six inches below the fuel level. The action of these tuyeres upon the fuel is to maintain a bright layer of fuel at the top of the furnace and without destroying the character of the furnace as a reducing furnace to make the action of the upper layers of the fuel essentially operative. In addition to the function of the upper row of tuyeres upon the character of the fire I employ them as a means for feeding the blue fume to the furnace; the fume in a nely divided condition is fed to the air blast entering the furnace through the upper tuyeres en tering the bright zone of fuel immediately below the top of the charge in admixture with ore and of course with the particles of blue fume separated from each other. The particles are rapidly smelted in contact with the incandescent carbon, depositing ne particles of metallic lead which particles are immediately subjected to the action of oxygen and 'the sulphur present and recombined therewith with the formation of lead sulphate and oxide of lead driven olf as a sublimate or a fume. Owing to the fine state of division of the fume and the character of the fire in the furnace the particles of metallic lead are not agglomerated together in sufficient quantity to run down into the lower zones of the furnace but are substantially all driven off as a sublimate; and the fume thus produced is of the best possible character for use as a pigment.

In the drawing I have represented in vertical section a furnace embodying my new construction and adapted for use in my process; showing also in connection with it a cooling and screening system indicated in a conventional style.

A indicates the furnace of the low cupola type, the sides of which, indicated at A', are formed of water jackets,'while A2 indicates a tap at the bottom of the furnace through which the slag and metal, if any is formed, are drawn off.

B indicates a blast pipe from which extend tuyeres B entering the furnace near the bottom in the usual way.

C indicates the feed door of the furnace.

v D is a blast pipe from which exten ds a series of tuyeres D entering the furnace in its upper part a short distance below the level of thefuel charge, which level is indicated at a.

E indicates a blast fan having a delivery nozzle E which communicates with the pipe D; and F is a hopper communicating with the fan E through which the finely divided blue fume is fed into the blast.

Gis a liue preferably of refractory material and into which the gases and fumes generated in the furnace pass therefrom. Thev with a screening system, for instance a series of fabric bags as indicated at N.

The operation of the system is familiar and will be understood without further description.

I-Iaving now described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. The method of making a white pigment from lead fume whichconsists in blowing the finely divided fume in admixture with air into the upper part of the fuel charge in a low cupola furnace to eect the reduction, recombination and sublimation of the fume and separating the re-sublimed fume fromfurnace gases.

2. In combination,with a low cupola furnace having tuyeres for maintaining combustion charges, and a flue and screen system connected therewith, of a second series of tuyeres entering the furnace below but near lthe level of the fuel charge, a blast fan arranged to force air through the upper tuyeres,

and a fume-feeding device arranged to feed lead fume to the said tuyeres.

EAYRE O. BARTLETT.

Witnesses:

ALF. H. FABER, D. STEWART. 

